From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A9F103128D5; Tue, 2 Sep 2025 13:39:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756820381; cv=none; b=asRTJ+RA5mJf1NYEwOk3sOFTYmocDx8+IyCl3HUcgA8s8SeNokhrugec7DEUmcR4MrPKmfdxG5w24C31z+lwy0lPGtLOO+9EuK/UrCN6gTozD6NT5QF2cYkciB+PlDgDGS8cXi1rkORQ9vZNpe98+IxtVYu5903RtYAfU1Gsf2A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756820381; c=relaxed/simple; bh=Pt5FSQxhRTPzFxg7URdJXRRjDlYcdDMl+oSyQpKpbMc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=J3sjLyQxvtGPCLmCWh7jbbnAv8J7aQCIWSp0MWmp2BNa/u/H9aXlrKv1gSgrS+B5vLYY9IT8AyW1mxyGjIvKkUNEwVAss3S8zRl0/mlCjg28A+RCndoy1kIj2vlnnbiu0yaLjvKjnDTL3iRrUtRBxV2tnZAmN8VzoRDoVwfgFPU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=iHPEhgM7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="iHPEhgM7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1458C4CEF4; Tue, 2 Sep 2025 13:39:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756820381; bh=Pt5FSQxhRTPzFxg7URdJXRRjDlYcdDMl+oSyQpKpbMc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iHPEhgM7vLjI7DnZ21rZl5gDhpUWmT8yQYrragsESH+E81ja1aeqdh3hJt9sXWQq0 RjeDzWJWQCrz6D+ikCjsxgTbYey6/OewWs1Ps/c3cNedP2NZdG+BvMiIJgtWk0tXVG G6evHqBZIG+2pxSEPHe1YLo1YhpPwMZzOuIEiqsY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jeff Layton , Joe Quanaim , Andrew Steffen , Trond Myklebust Subject: [PATCH 6.1 11/50] NFS: Fix a race when updating an existing write Date: Tue, 2 Sep 2025 15:21:02 +0200 Message-ID: <20250902131930.965591805@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250902131930.509077918@linuxfoundation.org> References: <20250902131930.509077918@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Trond Myklebust commit 76d2e3890fb169168c73f2e4f8375c7cc24a765e upstream. After nfs_lock_and_join_requests() tests for whether the request is still attached to the mapping, nothing prevents a call to nfs_inode_remove_request() from succeeding until we actually lock the page group. The reason is that whoever called nfs_inode_remove_request() doesn't necessarily have a lock on the page group head. So in order to avoid races, let's take the page group lock earlier in nfs_lock_and_join_requests(), and hold it across the removal of the request in nfs_inode_remove_request(). Reported-by: Jeff Layton Tested-by: Joe Quanaim Tested-by: Andrew Steffen Reviewed-by: Jeff Layton Fixes: bd37d6fce184 ("NFSv4: Convert nfs_lock_and_join_requests() to use nfs_page_find_head_request()") Cc: stable@vger.kernel.org Signed-off-by: Trond Myklebust Signed-off-by: Greg Kroah-Hartman --- fs/nfs/pagelist.c | 9 +++--- fs/nfs/write.c | 66 ++++++++++++++++------------------------------- include/linux/nfs_page.h | 1 3 files changed, 29 insertions(+), 47 deletions(-) --- a/fs/nfs/pagelist.c +++ b/fs/nfs/pagelist.c @@ -233,13 +233,14 @@ nfs_page_group_unlock(struct nfs_page *r nfs_page_clear_headlock(req); } -/* - * nfs_page_group_sync_on_bit_locked +/** + * nfs_page_group_sync_on_bit_locked - Test if all requests have @bit set + * @req: request in page group + * @bit: PG_* bit that is used to sync page group * * must be called with page group lock held */ -static bool -nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit) +bool nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit) { struct nfs_page *head = req->wb_head; struct nfs_page *tmp; --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -154,20 +154,10 @@ nfs_page_set_inode_ref(struct nfs_page * } } -static int -nfs_cancel_remove_inode(struct nfs_page *req, struct inode *inode) +static void nfs_cancel_remove_inode(struct nfs_page *req, struct inode *inode) { - int ret; - - if (!test_bit(PG_REMOVE, &req->wb_flags)) - return 0; - ret = nfs_page_group_lock(req); - if (ret) - return ret; if (test_and_clear_bit(PG_REMOVE, &req->wb_flags)) nfs_page_set_inode_ref(req, inode); - nfs_page_group_unlock(req); - return 0; } static struct nfs_page * @@ -239,36 +229,6 @@ static struct nfs_page *nfs_page_find_he return req; } -static struct nfs_page *nfs_find_and_lock_page_request(struct page *page) -{ - struct inode *inode = page_file_mapping(page)->host; - struct nfs_page *req, *head; - int ret; - - for (;;) { - req = nfs_page_find_head_request(page); - if (!req) - return req; - head = nfs_page_group_lock_head(req); - if (head != req) - nfs_release_request(req); - if (IS_ERR(head)) - return head; - ret = nfs_cancel_remove_inode(head, inode); - if (ret < 0) { - nfs_unlock_and_release_request(head); - return ERR_PTR(ret); - } - /* Ensure that nobody removed the request before we locked it */ - if (head == nfs_page_private_request(page)) - break; - if (PageSwapCache(page)) - break; - nfs_unlock_and_release_request(head); - } - return head; -} - /* Adjust the file length if we're writing beyond the end */ static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count) { @@ -625,14 +585,32 @@ nfs_lock_and_join_requests(struct page * * reference to the whole page group - the group will not be destroyed * until the head reference is released. */ - head = nfs_find_and_lock_page_request(page); +retry: + head = nfs_page_find_head_request(page); if (IS_ERR_OR_NULL(head)) return head; + while (!nfs_lock_request(head)) { + ret = nfs_wait_on_request(head); + if (ret < 0) { + nfs_release_request(head); + return ERR_PTR(ret); + } + } + ret = nfs_page_group_lock(head); if (ret < 0) goto out_unlock; + /* Ensure that nobody removed the request before we locked it */ + if (head != nfs_page_private_request(page) && !PageSwapCache(page)) { + nfs_page_group_unlock(head); + nfs_unlock_and_release_request(head); + goto retry; + } + + nfs_cancel_remove_inode(head, inode); + /* lock each request in the page group */ for (subreq = head->wb_this_page; subreq != head; @@ -853,7 +831,8 @@ static void nfs_inode_remove_request(str struct nfs_inode *nfsi = NFS_I(inode); struct nfs_page *head; - if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) { + nfs_page_group_lock(req); + if (nfs_page_group_sync_on_bit_locked(req, PG_REMOVE)) { head = req->wb_head; spin_lock(&mapping->private_lock); @@ -864,6 +843,7 @@ static void nfs_inode_remove_request(str } spin_unlock(&mapping->private_lock); } + nfs_page_group_unlock(req); if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags)) { nfs_release_request(req); --- a/include/linux/nfs_page.h +++ b/include/linux/nfs_page.h @@ -148,6 +148,7 @@ extern void nfs_join_page_group(struct n extern int nfs_page_group_lock(struct nfs_page *); extern void nfs_page_group_unlock(struct nfs_page *); extern bool nfs_page_group_sync_on_bit(struct nfs_page *, unsigned int); +extern bool nfs_page_group_sync_on_bit_locked(struct nfs_page *, unsigned int); extern int nfs_page_set_headlock(struct nfs_page *req); extern void nfs_page_clear_headlock(struct nfs_page *req); extern bool nfs_async_iocounter_wait(struct rpc_task *, struct nfs_lock_context *);